Method of manufacturing flat viscose fibers



United States Patent Japan No Drawing. Filed Aug. 12, 1963, Ser. No. 301,625

Claims priority, application Japan, Aug. 18, 1962, 37/ 35,829

3 Claims. (Cl. 264-487) The present invention relates to a method of manufacturing tubular and fiat viscose fibers having lusters and excellent flatness characterized in that a viscose having an ammonium chloride value of more than 16 containing 12-50% of water swelling high molecular substance based on the cellulose in the viscose, and 24% of alkali carbonate based on the viscose is spun into a spinning bath containing sulfuric acid and sulfates.

Viscose fibers have recently been used in largequantity for making paper and non-woven cloths. Ordinary viscose fibers, however, different from wooden fibers-and bast fiber, are difficult to be fibrillized by beatingand also the adhesion between fibers can not be developed by the action of heat and water so that it is difiicult to produce papers from viscose fibers alone, and it is necessary to add some other binder.

In order to solve the above difiiculties it has recently gether more intimately to cause van der Waals bond or hydrogen bond between cellulose molecules constituting the fiber, thereby providing papers of sufiicient strength by the intermolecular bonding force. The hollow fiat viscose fibers obtained by known processes require strict manufacturing control, and even then sufliciently flat viscose fibers are difficult to obtain. In general a paper of sufiicient strength can not be obtained by using such fibers.

Moreover when the monofilament denier 5 becomes large the flatness becomes gradually worse and even when it is sufliciently flat the adhesion of fibers with each other becomes insufficient and the spacing between H fibers prevents the intermolecular bonding force of cellulose to act between each fiber so that such fibers alone are diflicult to make papers.

In heretofore known hollow flat viscose fibers, usually if monofilament denier is more than 3 denier the average length (average thickness) of short axis of the flat part becomes more than 4 1.. The, self adhering property between fibers is almost or perfectly lost and when the paper made of heretofore known hollow flat viscose fibers only, is wetted, the inter-fibrous binding force is lost and the fiber is dispersed into water.

According to the present invention, by making tubular flat viscose fibers containing water swelling high molec: ular substance the inter-fibrous binding force when paper is manufactured is increased so that the manufacturing conditions are not critical. The invention also provides fibers having excellent flat condition, luster and superior self-adhering property. Moreover the tubular flat viscose fibers obtained by the method of the invention enables manufacture of paper having sufiicient strength without adding any other binder even when monofilament denier becomes larger and the average length (average thickness) of the short'axis of'the flat part becomes 3,318,990 Patented May 9, 1967 comparatively large and can perfectly obviate the basic disadvantages of heretofore known hollow flat viscose fibers in which the self-adhering property and paper making possibility in the large denier filaments are lost. Further, the paper obtained by using the tubular flat viscose fibers obtained by the method of the invention only does not lose the inter-fibrous binding force when wetted again but maintains the configuration of paper.

The hollow flat viscose fibers manufactured by heretofore known process and papers manufactured by such fibers have luster but the paper manufactured by the tubular flat viscose fiber and the paper manufactured by the fiber of the present invention have superior luster, and by hot-pressing the wet paper when manufactured the similar effect can be developed without applying treatment with surface coating agent.

The waterswelling high molecular substances in the present invention means, for instance, polyvinyl alcohol (abridged as PVA hereafter) which is swelled by water at room temperature but soluble in warm water or hot water and PVA'derivatives, or hemi cellulose, methyl cellulose, ethyl cellulose, cyanoethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and the like socalled alkali soluble cellulose derivatives. The tubular flat viscose fiber in the invention means such fiber -con taining 245% of such water swelling high molecular substance and at least 60% of the total length of the fiber have tightly adhered inner surfaces without hollow portion and consists of a tubular flattened portion of which the long axis of the cross section of the fiber is at least 5 times that of the short axis. The content of the water swelling high molecular substance in the fiber depend on the kinds, object and fitness etc. of the fiber but usually desirable to be of 2 to 50% of the weight of regenerated cellulose in fiber, prefer-ably 5 to 30%.

l The fiber-having good luster and self-adhesivity neces-. sitates such condition that the internal surfaces of the tubular flattened portion are almost preferably adhered without gap and upper and rear surfaces are smooth and substantially parallel and also it has possibly large flat- I ness and the long axis of the cross section of the'fiber the fiber there is sometimes'preferable to mix 20 to 30% of solid fiber. For instance, if it is desired to obtain a paper having high splitting strength it is better to mix solid fiber rather than to make paper with flat fiber only. The tubular flat fiber of the invention may be obtained by spinning a younger ripening degree viscose containing 2 to 50% (based on the cellulose in viscose) of water swelling high molecular substance and 2 to 4% (based on the produced viscose) of alkali carbonate and having an ammonium chloride value of more than 16 into a spinning bath containing sulfuric acid and sulfate. The water swelling high molecular substance and alkali carbonate may be added at any suitable stage of viscose process and also may be added simultaneously or separately. stance such as PVA it is preferable to react it with carbon disulfite to provide PVA xanthate solution. It is not necessary to use special viscose composition but it is preferable to take younger age viscose in case of spinning and an ammonium chloride value of about 20 is suitable.

In spinning such viscose it is usual to use spinning bath consisting of sulfuric acid, sodium sulfate and zinc L sulfate, yet in this case the existence of zinc sulfate is In case of water swelling high molecular subvuted by magnesium sulfate, aluminum sulfate in combiiation and the concentration of sulfate is preferably high n order to prevent the dissolving of water swelling high nolecular substance in viscose and to obtain superior flat liscose fibers the temperature and acidity of spinning bath are preferably high.

The fibers obtainable by the method of the invention nay be used, besides for making paper, for non-woven :loths or clothes, domestic purposes, wall papers and Jther fibers for building construction.

Example 1 PVA having polymerization degree 1,700 was dissolved In hot water and added with caustic soda and carbon disulfide and mixed by stirring at 20 C. for 90 minutes to xanthat-e PVA. The PVA xanthate solution thus obtained :ontaining 8.5% PVA and alkali is added with viscose nade by a conventional process consisting of 8.5% celluose and 5% alkali at a rate of 2:8 and then added hereto with 3% (based on the produced viscose mixture) )f sodium carbonate and agitated to dissolve.

After filtered and defoamed, the solution having aging legree of 18 ammonium chloride value was spun through L nozzle having 3,000 holes, 0065 mm. dia. into the pinning bath consisting of 12% sulfuric acid, 2.5% zinc :ulfate and 25% sodium sulfate at 60 C. and the filanent thus spun was stretched for 40% into a hot water )ath and after taken up at a spinning speed of 50 m./ min. t was cut to a length of 4 mm. By changing delivery uantity of viscose under this condition tubular flat fibers iaving monofilament of 0.7 denier, 1.0 denier, 2.5 denier, idenier and 8 denier were obtained.

For the sake of comparison a conventional solution )f viscose having the composition of 8.5% of ordinary viscose cellulose and 5% of alkali added with 3% of :odium carbonate same as above example, without adding ?VA xanthate solution, and spun under the same condiion and prepared same tubular flat fibers having differ- :nt deniers.

besides caustic soda, 3.5% (based on the produced visc ose) of sodium carbonate and 10% (based on cellulose) of carboxy methyl cellulose and agitated at 15 C. for 3 hours to dissolve and 8% of thus produced cellulose and viscose of 8% of all alkalis were spun at an ammonium chloride'value 22 into the spinning solution same as in Example 1. The fiber coming out of the spinning solution was stretched for into a bath of 1% sulfuric acid at 50 C., then wound up at a speed of 30 m./min. and cut to a length of 4 mm. The fiber had monofilament denier of 1.5 and flat tubular section having perfectly adhered inner surfaces and the short axis of its cross section of 2.5 and long axis of 56,11.. A paper was made by using this fiber by the same manner as in Example 1, having the weight 52.45 g./m. thickness 0.08 mm., breaking length 38 km. and tear factor 190.

The paper made of the flat tubular fibers obtained under the same condition as above from viscose not containing carboxy methyl cellulose showed the weight of 53.18 g./m. thickness of 0.12 mm., breaking length of 1.35 km. and tear factor 220. With fibers of the method of the invention a very thin paper was produced having a acid and sulphate, said viscose containing 2 to 50%,

based on the weight of cellulose in viscose, of a water swelling substance selected from the group consisting of polyvinyl alcohol, polyvinyl alcohol derivatives, and alkali soluble celuose derivatives and containing 2 to 4%, based on the weight of viscose, of alkali carbonate, whereby tubular flat viscose fibers are obtained.

2. A method according to claim 1, wherein the Water swelling substance is seletced from the group consisting The conditions of flatness of each fiber is as shown in 40 of herni cellulose, methyl cellulose, ethyl cellulose, cyanohe next table.

ethyl cellulose, and hydroxyethyl cellulose.

Monofilament Adhesion of internal Short axis of Long axis of Long axis/ dr. Kind of filament surface cross section cross section short axis I.7 The invention Good 1. 6 43 26. 9 Contrast do 1. 9 38 20.0 ..5 The invention dn 2. 3 23. 9 Contrast do 2. 8 47 17. 8 5.5 The invention do 3. 0 58 19.4 Contrast Somewhat no good 3. 6 61 16.9 The invention ood. 6. 2 71 11.5 Contrast No good 7. 0 70 10.0 The invention Somewhat no good 8. 8 93 10. 6 Contrast No goo 9. 2 84 9. 2

The fiber prepared by the :method of the invention is ightly adhered in the internal surface and has a greater latness compared with a conventional fiber and more- )ver even if the monofilament denier becomes larger good lat fibers can be obtined. The fibers obtained by the nethod of the invention were dispersed in water each ndependently and thereafter without adding other binder taper is made according to the TAPPI process by manual vorking and the wet paper thus obtained was pressed and ried by a hot press with the pressure of 0.5 kg./cm. nd at a temperature of 100 C., then as the result, all mapers obtained from the fibers of the mixed spun PVA of he invention showed sufiicient strength and excellent urface luster.

On the other hand, in a fiat fiber obtained from viscose lithout mixing with PVA, When monofilament denier is ass than 2.5 a paper may be made but with the flat iber of 5 denier and 8 denier no paper could be manuactured.

Example 2 3. A method according to claim 1, wherein the fiber is made from a sodium xanthate dissolved by addition of caustic soda, alkali carbonate and carboxy methyl cellulose.

References Cited by the Examiner UNITED STATES PATENTS 1,464,048 8/1923 Rousset 161178 2,085,513 6/1937 Steindortf et a1 106164 2,162,460 6/ 1939 Maxwell. 2,165,393 7/1939 Lilienfeld 106-164 2,176,085 10/ 1939 Lilienfeld 106164 2,201,663 5/ 1940 Ellsworth et al. 2,265,915 12/ 1941 Lilienfeld. 2,267,217 12/1941 Reichel. 2,783,158 2/ 1957 Entwistle et al.

2,796,656 6/1957 Schappel et al. 264198 X 2 ,835,551 5/1958 Kosuge 161178 X FOREIGN PATENTS 37-5810 6/1962 Japan.

ALEXANDER H. BRODMERKEL, Primary Examiner. J. H. WOO, Assistant Examiner. 

1. A METHOD OF MANUFACTURING TUBULAR FLAT VISCOSE FIBERS, WHICH COMPRISES SPINNING VISCOSE HAVING AN AGING DEGREE REPRESENTED BY AN AMMONIUM CHLORIDE VALUE OF MORE THAN 16 TO A SPINNING SOLUTIN CONTAINING SULPHURIC ACID AND SULPHATE, SAID VISCOSE CONTAINING 2 TO 50%, BASED ON THE WEIGHT OF CELLULOSE IN VISCOSE, OF A WATER SWELLING SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF POLYVINYL, ALCOHOL, POLYVINYL ALCOHOL DERIVATIVES, AND ALKALI SOLUBLE CELUOSE DERIVATIVES AND CONTAINING 2 TO 4%, BASED ON THE WEIGHT OF VISCOSE, OF ALKALI CARBONATE, WHEREBY TUBULAR FLAT VISCOSE FIBERS ARE OBTAINED. 